Wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using orthogonal frequency-division multiple access (OFDMA) in a downlink (DL) transmission and single carrier frequency division multiple access (SC-FDMA) in an uplink (UL) transmission. Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third generation partnership project (3GPP) long term evolution (LTE) and LTE-Advanced (LTE-A), the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which is commonly known to industry groups as WiMAX (Worldwide interoperability for Microwave Access), and the IEEE 802.11 standard, which is commonly known to industry groups as Wi-Fi. It should be noted that LTE and LTE-A are the same technology, but LTE-A is used to distinguish releases 10 and 11 (current version) of the standard from earlier releases.
In 3GPP radio access network (RAN) LTE and LTE-A systems, the node can be a combination of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), which communicates with the wireless device, known as a user equipment (UE). Examples of a UE include a mobile terminal, a tablet computer, a personal digital assistant (PDA) and a machine-type communication (MTC) device. The downlink (DL) transmission can be a communication from the node (or eNodeB) to the wireless device (or UE), and the uplink (UL) transmission can be a communication from the wireless device to the node.
In LTE and LTE-A, data can be transmitted from the eNode B to the UE via a physical downlink shared channel (PDSCH). A physical downlink control channel (PDCCH) and/or enhanced physical downlink control channel (EPDCCH) can be used to transfer downlink control information (DCI) that informs the UE about resource allocations or scheduling related to downlink resource assignments on the PDSCH, uplink resource grants, and uplink power control commands. The PDCCH can be transmitted prior the PDSCH in each subframe transmitted from the eNode B to the UE. The EPDCCH is transmitted on the same OFDM symbols of the subframe as PDSCH as illustrated by FIGS. 3A and 3B described below. If resource allocation information for PDSCH conveyed by PDCCH or EPDCCH is not received correctly, the decoding of the corresponding PDSCH is likely to fail. Since failed decoding of PDSCH will be detrimental to system performance, the reliability of accurate receipt of PDCCH and EPDCCH is an important system requirement. It is known to improve reliability of these downlink control channels using transmission techniques such as channel coding, spatial diversity and frequency diversity.
Interference may occur when a User Equipment (UE) such as a mobile terminal communicates with a serving base station in a wireless network environment. For example, a neighboring base station may be communicating with other UEs concurrently with the serving base station communicating with a given UE and these communications from the neighboring base station can cause interference issues for the given UE communicating with the serving base station.
As advances in wireless communication technology progress, it is desirable to improve the capacity of LTE-A networks by deployment of heterogeneous networks to achieve cell-splitting gains and Multi-User Multiple-Input Multiple-Output (MU-MIMO). It is expected that co-channel interference originating from either inter-cell (between different cells) or co-scheduled intra-cell (same cell) users will be an important limiting factor in achieving higher network capacity.
It is known to implement interference mitigation at the network side, for example, at the transmitting base station, by employing coordinated multi-point techniques (CoMP). These CoMP techniques involve base transceiver stations being grouped together such that base transceiver stations from multiple cells can transmit signals to the UE and receive signals from the UE.
It is known in communication systems such as LTE, which employs Single User MIMO to use maximum likelihood demodulation to jointly decode two communication signals corresponding to two data streams transmitted substantially simultaneously by the same base station to the same UE. This mitigates intra-cell interference. In this case the UE has information on the modulation scheme used for both of the received data streams.